Foam protection of plant life

ABSTRACT

There is described a foam concentrate from which foams to be used to protect vegetation, for example from frost can be produced. The concentrate comprises a neutralized protein hydrolysate stabilized with specified proportions of iron and lignosulfonate. A method of protecting vegetation using the above foams is also described.

United States Patent Butler [45] June 13, 1972 FOAM PROTECTION OF PLANTLIFE [56] References Cited [72] Inventor: James W. Butler, Stittsville,Ontario, UNITED STATES PATENTS Canada I 2,324,951 7/1943 Ratzer..252/307 [73] Assignee. Lnurentian Concentrates Llnllttd, Ontano, 2 4137 2 94 Urquhart 252 307 cmda 2,433,625 12/1941 Raspet .mzsz/sov [22]Filed; Feb. 7, 1969 2,875,555 3/l959 Theigs et al.... ....252/32.958.658 1 H1960 McIntosh ..252/3 [2i] Appl. No.: 797,689

Primary Examiner-John D. Welsh 30 Foreign Application Priority DataAtwmeyFeflwr-swnhaugh &

Dec 12, 1968 Canada ..037,6l0 57 ABSTRACT [52 1 us. Cl ..252/307, 47/2,252/350, There i described a f m n n r fr m h h f ms to be 239/2 used toprotect vegetation, for example from frost can be [51] Int. Cl ..A01g13/00 pr Th ncentrate mprise a n ralized pr ein [58] Field of Search..252/3, 307, 350; 47/2 hydrolysate stabilized with specifiedproportions of iron and lignosulfonate. A method of protectingvegetation using the above foams is also described.

17 Claims, No Drawings BACKGROUND OF THE INVENTION I. Field of theInvention This invention relates to concentrates to be used in theproduction of foams and to a method of protecting vegetation usingfoams.

2. Prior Art The use of foams to protect crops is known but it has notcome into general use. The principle problem has been to produce a foamthat is stable for a sufficient period.

For such a foam to be effective it must be present on the vegetationwhen frost occurs. It must be in a condition capable of offeringprotection from the frost, and must retain this condition throughout thecritical frost period. Following the frost period the foam must bereadily dispersable either by natural means (sun and wind) or byavailable mechanical means (agitation, water spray or airjet). Inpractice the foam could be applied immediately following a frostwarning. Such a warning may be l2 hours before the frost so that foamapplication may take place at midday. The foam is then expected to offerprotection until sun rise the next day. This early foam applicationbecomes obligatory when the acreage to be covered is large. Thus thefoam should be stable for at least 18 hours, in spite of the fact thatfor smaller applications a life of as little as 4 hours would suffice.This 18 hours minimum life should be possible not only in the dark,still, cold atmospheric conditions associated with frost onset but alsoin the variable daytime atmospheric conditions likely to be presentimmediately before frost onset in spring or fall.

A foam to be used for frost protection should also have structuralstrength. if applied to vegetation in the form of a row crop in springor fall, a wide swath, a bush or hedge, a branch or a tree, the blanketmust bridge reasonable gaps without collapse. Furthermore it shouldretain this strength without dimensional alteration throughout thecritical period. Since a foam represents air bubbles surrounded by anaqueous solution it is evident that any loss of the aqueous solutionmust lead to a weakening of the bubble walls and thus the foam itself.It is therefore imperative that loss of liquid by drainage should beminimal or nil. Loss of liquid by evaporation should be reduced orstopped by the surface characteristics of the foam or possibly by theapplication of a water vapor retaining coating to the foam.

Any foam to be used for frost protection must be entirely nontoxic andwithout deleterious effect on the development of the vegetation. A foamshould not reduce pollination, fruit set or development, yield, quality,or leaf production. Rather the reverse is to be hoped for. Further, anyremains of foam lcfi on ripe fruit should be completely harmless ifeaten.

Foams are extensively used in fire fighting. Most foam concentrates usedto produce firefighting foams use protein hydrolysates to obtain therequired fire resistance and strength in the final foam. These proteinhydrolysates are produced by the action of, for example, the hydroxidesof sodium or calcium in aqueous solution on a variety of proteins, forexample, blood, feather meal, hoof and horn meal, fish meal and oil seedcakes, at either atmospheric or elevated pressures. Following hydrolysisthe clear solution is neutralized and ifnecessary concentrated. At somestage in this process the foam composition is stabilized. Virtually allmodern foam compounds contain salts of ferrous iron to effectstabilization although other metals are occasionally used for specificpurposes. The extent of stabilization is limited by the insolubility ofthe protein-iron complexes formed upon over-stabilization. In general itmay be said that the maximum amount ofiron (as Fe) is about percent ofthe protein nitrogen present (as N).

It is known that protein based fire-fighting concentrates can includesoluble lignosulfonates. These lignosulfonates worsen the fire-fightingproperties of the foam produced from the concentrate and add littleworthwhile to the other properties of the foam.

SUMMARY OF THE INVENTION The present invention provides a foamconcentrate from which foams suitable for the protection of crops can beformed.

The present invention provides a foam concentrate that comprises aneutralized protein hydrolysate containing a stabilizer (a) sufficientferrous salt to provide 20 to parts of iron per I00 parts of proteinnitrogen and (b) sufficient of a lignosulfonate to provide I00 to i000parts of lignosulfonate, measured as dry salt, per I00 parts of proteinnitrogen, all parts being by weight.

Commercially obtainable lignosulfonates may be used but those of sodiumor ammonium are preferred.

The neutralized protein hydrolysate used may be of any of those used toproduce fire-fighting foams.

The addition of gelatin wholly or partly to replace the lignosulfonategives a concentrate capable of producing a fairly satisfactory foam. Thegelatin is preferably present in a partially alkaline hydrolyzed form.

Ferrous compounds that may be used include any ferrous compound that isnot toxic to the plants to be protected. F errous sulfate and ferrouschloride have proved useful.

The preferred ratio of protein nitrogen:ironzlignosulfonate isl00:50:250. Outside the preferred range, variations can lead toundesirable features, for example reduced expandibility, less desirablesurface characteristices, and less bubble wall strength but we have alsofound that the nature of the protein used to form the concentrate andwhich could have varied considerably in its initial processing can leadto a change in the ratio chosen in order to achieve optimum foamconditions.

The pH of the concentrate is reasonably important. A high pH can assistin the production of a clear concentrate but the diluted concentratesulTers severely since foam production is reduced. Low pH offer noimprovement and tend to render the compound unstable. pH 7 i 0.5 is theoptimum.

The production of a foam from the above concentrate may be by anytechnique capable of producing the desired foam. A technique that hasproved useful is to pass diluted concentrate and compressed air inappropriate proportions and at a pressure of about 10 lbs per squareinch through a conventional mixing device, for example a tube packedwith gauze. A preferred dilution of the concentrate is to a solutioncontaining 0.15 percent w/v protein nitrogen. However solutionscontaining between 0.1 percent and 0.3 percent w/v protein nitrogen cangive almost equally good results. For reasons of economy and in order toachieve structural strength it is desirable to incorporate the maximumvolume of air into the foam in the form of minute discrete bubbles.Generally the optimum is 29 parts of air to l part diluted concentrate,i.e., an expansion of 30, with variations governed solely by structuralfoam strength at the low level and by unmanageability at the high level.Generally this represents expansions of 25 and 45 respectively althoughthese values can be exceeded when circumstances warrant.

An improved foam may be produced if a soluble calcium salt is present inthe diluted concentrate. The improvement takes the form of enabling astiffer foam to be made whose surface characteristics are improvedgreatly by virtue of a layer of glazed foam. We have not been able tointroduce the calcium into the concentrate because of the grossdeterioration and eventual sludging that this produces. But calcium mayreadily be introduced into the dilute working solution and there effectits improvement.

Excess iron, over and above that acceptable in the concentrate, may beintroduced into the diluted concentrate. If preferred all the iron maybe introduced into the diluted concentrate rather than in theconcentrate, without losing any of its effectiveness.

Expansion improvers common to the foam producing art may be introducedif necessary to ensure the production of the desired expansion from theconcentrate.

The present invention also provides a method of protecting vegetationespecially from frost, that comprises applying to the vegetation a foamproduced by the above process. Foams made by the above process have afrost protection life far in excess of foam made from the originalprotein based concentrate, or from the concentrate plus the ironadditions with no addition of lignosulfonate or from the concentrateplus the lignosulfonate with no addition of iron. We have shown in factthat within definable limits the concentrates produced by this means canproduce a unique foam that is plastic. cohesive and adhesive whenproduced. Within a short time, normally is 2 minutes, the foam Sets up,"adopts a short consistency and in this form can shear, although plantmovement or wind does not achieve this unless grossly excessive. Foamsproduced using expansions greater than 25 do not lose, by gravitationallosses, any of the liquid from which they were made, sole losses ofliquid being by evaporation or by contact with a bibulous substrate.This is exceptional if not unique. Furthermore the surface of the foamtends to glaze and thereby restrict evaporation, although full summersun, which is seldom met under frost conditions, can overrule thiseffect and result in an increased evaporation loss. Natural destructionof the foam is a function of sunlight, sun heat, low humidity and wind.If none of these are present the life of the foam is greatly increased.Destruction and dispersal of the foam is by drying by evaporation fromthe outer surface and the blowing away of the dried layers or patches.

There are practical limits to the thickness of foam blanket required.Thus although the insulation properties of the foam are adequate enoughto permit a thinner blanket, the weakening of the foam surface due toevaporation from the surface indicates a minimum blanket thickness ofone inch. At the other extreme blankets over three inches in thicknessare too long lasting. Both these limits are approximate for normalspring or fall atmospheric conditions.

Successive foam layers on tomatoes and on strawberries, both sensitiveplants, have resulted in no harm whatsoever to the plants, or to theirdevelopment and fruit forming or yielding properties even with as manyas nine applications over a four week period in spring. Officialconfirmation that in the amounts that foam residues are likely to remainon ripe fruit there is no health hazard whatsoever has been received.

The invention will be described further in the following examples.

The concentrates used in the following Examples are prepared byappropriate dilution and addition of stabilizers according to theinvention to a protein hydrolysate prepared in the following manner:

Seven gallons of water were heated to 95 C with 9 lbs. of Slaked Limeadded and continually stirred, followed by the addition of 23 lbs. Hoofand Horn Meal. The temperature was brought up to 92-95 C and held for 5hours.

The mixture was filtered and the filtrate passed to vegetation stirredvessel where the pH was brought up to 7.0. The mixture was filteredagain.

The filtrate was concentrated by boiling to a Protein Nitrogen contentof 5.0 percent.

The skilled man will appreciate the above hydrolysate is prepared in anormal manner for the art. The hydrolysate can be replaced by any of theequivalent hydrolysates that are commercially available.

Example I A concentrate containing 2.8 percent protein nitrogen, 1.2percent iron (added as ferrous sulfate) and 7 percent sodiumlignosulfonate was used at a 6 percent dilution to form foams havingexpansions of 20, 25, 30, 40 and 50. These foams were applied by a handapplicator to 100 ft. rows of Fall field to matoes to give a 2 to 3 inchcover. The foams were applied at 5 pm. At l0 a.m. the next morning allfoam covers were still effective except where tall stems had brokenthrough. Visually the lowest expansions (20) was inferior in comparisonwith the others.

Example 2 The same solution as in Example I was used at 6 percentdilution and at expansions 25, 30 and 40, hand applied to the same rowsof tomatoes at 3 pm. to a thickness of 2 to 3 inches. The covercompletely protected the plants and fruit against a temperature of 23 F(5 inches from ground level) except where tall stems broke through thecover. Control plants without foam cover were completely destroyed.

Example 3 A series of tests were run using 5 percent and 6 percentsolutions of concentrates containing 2.4 to 3.3 percent nitrogen, 1.0 toL6 percent iron (added as ferrous sulfate) and 5 to 10 percentlignosulfonate made into foams of expansion 25 to 35. These foams wereapplied mechanically by a tractor drawn device to blanket tomatoes andstrawberry beds to a depth of l to 2 inches. The cover so obtainedremained viable for at least 18 hours except where tough weed stemsbroke through the cover.

The following example relate to laboratory investigational work designedprimarily to determine foam life under standard conditions. The foam inall these examples has been produced from a small foam-making branchpipeusing a premixed solution. The foam was set out in the open, on gravel,in the form of a 3 inch thick layer and observations made on itsbehavior.

Example 4 A concentrate containing 2.8 percent protein nitrogen, 1.35percent iron (added as ferrous sulfate) and 8 percent sodiumlignosulfonate was used in solutions containing 0.056 percent, 0.] l2percent and 0.168 percent nitrogen. The stiffness of the foams varieddirectly with the strength of the solutions. Foam from the weakestsolution set out in sunny conditions lasted about l2 hours where as fromthe other two solutions the foam was in good condition after 24 hours.

Example 5 A series of concentrates with 2.8 percent protein nitrogen,1.25 percent iron (added as ferrous sulfate) and with sodiumlignosulfonate between 2.8 percent and 8.4 percent were used as 5percent solutions to produce foams. All these foams were in goodcondition after 24 hours in sunny dry conditions. As made the foamsvaried, becoming less stiff as the lignosulfonate content increased. Theconcentrates showed no precipitation at levels of lignosulfonate at orabove 4.2 percent.

Example 6 A series of concentrates with 2.9 percent protein nitrogen 7.5ammonium lignosulfonate and with iron (added as ferrous sulfate) varyingfrom 0.85 percent to 1.6 percent were used at 6 percent solutions toproduce foams. At least l.l percent iron was shown to be required toensure a 24 hour active life for the foam but l.6 percent iron was shownto be in excess for this formulation since a sludge was developed in theconcentrate.

In all the above Examples ferrous chloride or any other ferrous compoundthat does not contain parts injurious to plants or animals could replacethe ferrous sulphate.

What I claim as my invention is:

l. A foam concentrate consisting essentially of a neutralized, proteinhydrolysate, containing as a stabilizer (a) sufficient water-solubleferrous salt non-toxic to plants to provide 20 to parts of iron per 100parts of protein nitrogen and (b) sufficient of sodium, calcium orammonium lignosulfonate to provide 100 to 1000 parts of lignosulfonate,measured as dry salt, per 100 parts of protein nitrogen, all parts beingby weight, the pH of the concentrate being about 7.

2. A concentrate as claimed in claim l in which the source ofneutralized protein hydrolysate is blood, horn, feathers or oil seedcake.

3. A concentrate as claimed in claim 1 in which the ferrous compound isferrous sulfate.

4. A concentrate as claimed in claim l in which the ratio of proteinnitrogen:iron:lignosulfonate is 10060250.

5. A concentrate as claimed in claim 1 in which the lignosulfate iswholly or partially replaced by gelatin.

6. A concentrate as claimed in claim 5 in which the gelatin is in apartially alkaline hydrolyzed form.

7. A concentrate as claimed in claim 1 in which the pH of theconcentrate is 7 i 0.5.

8. In a method of protecting vegetation comprising applying to thevegetation a foam produced from a diluted foam concentrate, theimprovement that comprises using as the concentrate a neutralizedprotein hydrolysate containing as a stabilizer (a) sufficientwater-soluble ferrous salt non-toxic to plants to provide 20 to lOOparts of iron per 100 parts of protein nitrogen and (b) sufficient of alignosulfonate to provide 100 to 1,000 parts oflignosulfonate, measuredas dry salt, per lDO parts of protein nitrogen, all parts being byweight.

9. A process as claimed in claim 8 in which the applied foam has athickness in the range of l to 3 inches.

10. A process as claimed in claim 8 in which the diluted concentratecontains between 0.1 percent and 0.3 percent weight w/v proteinnitrogen.

11. A process as claimed in claim 10 in which the diluted proteinconcentrate contains 0 l 5 percent w/v protein nitrogen.

12. A process as claimed in claim 8 in which the foam is produced byblowing a gas through the diluted foam concentrate.

13. A process as claimed in claim 12 in which the gas is air 14. Aprocess as claimed in claim 12 in which 29 parts of gas per 1 part ofdilute concentrate are used.

15. A process as claimed in claim 8 in which the diluted foamconcentrate also contains calcium.

16. A process as claimed in claim 8 in which the structural strength ofthe foam is such that the foam does not shear when in position on thevegetation under normal spring and fall conditions under which frost maybe expected.

17. A process as claimed in claim 8 in which the foams produced usingexpansions greater than 25 do not lose by gravitational losses any ofthe liquid from which they were made, sole losses of liquid being byevaporation or by contact with a bibulous substrate.

resen

2. A concentrate as claimed in claim 1 in which the source ofneutralized protein hydrolysate is blood, horn, feathers or oil seedcake.
 3. A concentrate as claimed in claim 1 in which the ferrouscompound is ferrous sulfate.
 4. A concentrate as claimed in claim 1 inwhich the ratio of protein nitrogen:iron:lignosulfonate is 100:50:250.5. A concentrate as claimed in claim 1 in which the lignosulfate iswholly or partially replaced by gelatin.
 6. A concentrate as claimed inclaim 5 in which the gelatin is in a partially alkaline hydrolyzed form.7. A concentrate as claimed in claim 1 in which the pH of theconcentrate is 7 + or - 0.5.
 8. In a method of protecting vegetationcomprising applying to the vegetation a foam produced from a dilutedfoam concentrate, the improvement that comprises using as theconcentrate a neutralized protein hydrolysate containing as a stabilizer(a) sufficient water-soluble ferrous salt non-toxic to plants to provide20 to 100 parts of iron per 100 parts of protein nitrogen and (b)sufficient of a lignosulfonate to provide 100 to 1,000 parts oflignosulfonate, measured as dry salt, per 100 parts of protein nitrogen,all parts being by weight.
 9. A process as claimed in claim 8 in whichthe applied foam has a thickness in the range of 1 to 3 inches.
 10. Aprocess as claimed in claim 8 in which the diluted concentrate containsbetween 0.1 percent and 0.3 percent weight w/v protein nitrogen.
 11. Aprocess as claimed in claim 10 in which the diluted protein concentratecontains 0.15 percent w/v protein nitrogen.
 12. A process as claimed inclaim 8 in which the foam is produced by blowing a gas through thediluted foam concentrate.
 13. A process as claimed in claim 12 in whichthe gas is air.
 14. A process as claimed in claim 12 in which 29 partsof gas per 1 part of dilute concentrate are used.
 15. A process asclaimed in claim 8 in which the diluted foam concentrate also containscalcium.
 16. A process as claimed in claim 8 in which the structuralstrength of the foam is such that the foam does not shear when inposition on the vegetation under normal spring and fall conditions underwhich frost may be expected.
 17. A process as claimed in claim 8 inwhich the foams produced using expansions greater than 25 do not lose bygravitational losses any of the liquid from which they were made, solelosses of liquid being by evaporation or by contact with a bibuloussubstrate.